title: Assessment of abdominal muscle function using the Biodex System-4. Validity and reliability in healthy volunteers and patients with giant ventral hernia.
abstract: BACKGROUND
  The decrease in recurrence rates in ventral hernia surgery have led to a redirection of focus towards other important patient-related endpoints. One such endpoint is abdominal wall function. The aim of the present study was to evaluate the reliability and external validity of abdominal wall strength measurement using the Biodex System-4 with a back abdomen unit.
  
  
  METHODS
  Ten healthy volunteers and ten patients with ventral hernias exceeding 10 cm were recruited. Test-retest reliability, both with and without girdle, was evaluated by comparison of measurements at two test occasions 1 week apart. Reliability was calculated by the interclass correlation coefficients (ICC) method. Validity was evaluated by correlation with the well-established International Physical Activity Questionnaire (IPAQ) and a self-assessment of abdominal wall strength.
  
  
  RESULTS
  One person in the healthy group was excluded after the first test due to neck problems following minor trauma. The reliability was excellent (>0.75), with ICC values between 0.92 and 0.97 for the different modalities tested. No differences were seen between testing with and without a girdle. Validity was also excellent both when calculated as correlation to self-assessment of abdominal wall strength, and to IPAQ, giving Kendall tau values of 0.51 and 0.47, respectively, and corresponding P values of 0.002 and 0.004.
  
  
  CONCLUSIONS
  Measurement of abdominal muscle function using the Biodex System-4 is a reliable and valid method to assess this important patient-related endpoint. Further investigations will be made to explore the potential of this technique in the evaluation of the results of ventral hernia surgery, and to compare muscle function after different abdominal wall reconstruction techniques.
authors.affiliation: Department of Surgery, CLINTEC, Karolinska Institutet, Karolinska University Hospital, Gastrocentrum K53, 141 86, Huddinge, Stockholm, Sweden.
authors.forename: U
authors.initials: U
authors.lastname: Gunnarsson
authors.forename: M
authors.initials: M
authors.lastname: Johansson
authors.forename: K
authors.initials: K
authors.lastname: Strigård
mesh_terms: D000009:Abdominal Muscles / Q000502:physiology* / Q000503:physiopathology*; D000328:Adult; D000368:Aged; D059026:Diagnostic Self Evaluation; D005260:Female; D006555:Hernia, Ventral / Q000503:physiopathology*; D006801:Humans; D008297:Male; D008875:Middle Aged; D053580:Muscle Strength / Q000502:physiology*; D053581:Muscle Strength Dynamometer; D015203:Reproducibility of Results; D011795:Surveys and Questionnaires